1. Field of the Invention
The present invention relates to a medical image diagnostic system to be used for diagnoses of breast cancer or the like by imaging mammary glands and breasts by using radiation and ultrasonic waves in combination. Further, the present invention relates to a medical imaging apparatus, a medical image storage apparatus, and a medical image display apparatus to be used in the medical image diagnostic system.
2. Description of a Related Art
Conventionally, an imaging method using radiation (X-ray, α-ray, β-ray, γ-ray, electron ray, ultraviolet ray, or the like) is utilized in various fields, and particularly, in the medical field, the method is one of the most important means for diagnoses. Radiation images obtained by X-ray imaging (X-ray mammography) of mammary glands and breasts for breast cancer diagnoses are useful for finding calcification as a precursor, but finding calcification may be difficult depending on the age of a subject. Accordingly, it has been studied to use radiation and ultrasonic wave in combination to make diagnoses based on both radiation images and ultrasonic images. X-ray mammography and ultrasonic imaging have the following features, respectively.
X-ray mammography is suitable for exposing calcification as one of early symptoms of a cancer, and enables detection with high sensitivity and high resolving power. Especially, in the case where mammary gland tissues have become atrophied and replaced with fat (so-called “fat breast”) as is the case of postmenopausal women, more information can be obtained by X-ray mammography. However, the X-ray imaging has a disadvantage that detection capability of specific natures of tissues (tissue properties) is low.
Further, in an X-ray image, mammary glands are expressed in homogeneous soft tissue density, and thus, the detection of tumor mass is difficult for the case where mammary glands have developed (so-called, “dense breast”) as is the case of adolescent to premenopausal women. Furthermore, in X-ray mammography, only two-dimensional images can be obtained in which an object to be inspected as a solid is projected on a plane. On this account, even when a tumor mass is found, it is difficult to grasp information on the locations in the depth direction, size, and so on of the tumor mass.
On the other hand, in ultrasonic imaging, specific natures of tissues (e.g., the difference between a cystic tumor and a solid matter) can be detected, and also, a lobular cancer can be detected. Further, real time observation of images and three-dimensional image generation are possible. However, ultrasonic imaging examination often depends on the skill of an operator such as a doctor in accuracy and provides low reproducibility. Further, it is difficult to observe minute calcification in an ultrasonic image.
As described above, X-ray mammography examination and ultrasonic imaging examination have both merits and demerits, and it is desirable that both examinations are performed for reliably finding breast cancer.
As a related technology, Japanese Patent Application Publication JP-P2005-312770A discloses an ultrasonic diagnostic apparatus capable of displaying ultrasonic images for observation within a body of an object to be inspected with guide images anatomically and precisely corresponding to the ultrasonic images. The ultrasonic diagnostic apparatus includes image processing control means for generating guide images corresponding to anatomic location and orientation of two-dimensional ultrasonic images based on anatomic image data stored as anatomic image data of a human body in advance, and display means for displaying a plurality of various images including the guide images and two-dimensional ultrasonic images. However, JP-P2005-312770A does not disclose that plural images obtained by respectively using plural different imaging modalities are correlated and displayed.